There is increasing demand for high-powered server computers for networks in general, and in particular for the Internet. The Internet is a giant network made up of many smaller networks interlinked through the use of devices such as bridges and gateways. In theory, any computer connected to the Internet is capable of exchanging information with any other computer that is connected to the Internet. However, since computers often contain sensitive information, many computers and networks have security schemes that restrict the exchange of information among computers to various degrees.
Since the Internet represents a very powerful structure through which to disseminate information, a number of services have evolved which make use of the Internet to pass information from one computer to another. Examples of these services are FTP, News, Gopher, and the World Wide Web (or WWW as it will be referred to hereafter).
The WWW is one of the more well known, and most quickly expanding, of these services. The WWW supported by the Internet is capable of combining technologies such as voice, video and text, and presenting them in an on-demand, interactive fashion to anyone connected to the Internet. In essence, the WWW allows anyone connected to the Internet with a computer that has the appropriate software and hardware configuration to retrieve any HyperMedia document that has been made available anywhere on the Internet. The HyperMedia document is received as a file representing a block of information, and within that file are hyperlinks to other documents (or blocks of information) which may, for example, contain texts, sounds, images or movies.
As the computer receiving the HyperMedia document constructs the document for display to the user, it may use some of these hyperlinks in order to receive other files necessary to complete the display. For instance, hyperlinks may be used to access image files which are to be displayed as part of the document. Once the document has been constructed by the client computer and displayed to the user, the user may have the opportunity to select hyperlinks, for example by using a mouse or other input device to select a word or image on the screen, in order to request the document referenced by that Hyperlink.
As more and more people have started to use Internet services such as WWW, so the demands on the server computers has increased. In order to cope with these demands, parallel computers have started to be used as servers, these computers having a plurality of processors arranged to provide the service. By use of the multiple processors, very high volumes of server requests can be handled. An example of such a parallel computer is the IBM RISC System/6000 SP machines (IBM and RISC System/6000 are registered Trade Marks of International Business Machines Corporation).
However, a problem that arises in use of such parallel servers is that of balancing the incoming client traffic across the processors that are collaborating in the parallel system to serve documents (such as Web pages in WWW) and run service-based applications. With existing Load-Balancing mechanisms, there can be times when one particular processor becomes the focus of a large amount of traffic for a period of time. The technical term for this is that the processor gets "toasted" . In this condition, the processor is overwhelmed by client requests, and grinds to a virtual halt, taking up to several minutes to service one request.
It is hence an object of the present invention to provide a mechanism to alleviate unbalanced load across the processors, thereby helping to avert this toasting effect.